Wound-inducible promoter from poplar is responsive to fungal infection in transgenic potato

Abstract

Regulated transgene expression, whereby a promoter is specifically activated in response to pathogen invasion or pest attack, has distinct advantages for genetic engineering disease/pest resistant traits in plants. We constructed plant transformation vector using the β-glucuronidase (GUS) reporter gene system and evaluated the spatiotemporal transcriptional activity of a wound-inducible win3.12 promoter from hybrid poplar (Populus trichocarpa × Populus deltoides) in transgenic potato plants in response to mechanical wounding, elicitor treatment and fungal infection. In addition, a highly efficient, petiole-based regeneration protocol for potato was developed. Results show that an 823-bp truncated form of the poplar promoter (designated win3.12T) was sufficient to confer systemic, wound-regulated transgene expression in potato. A positive correlation between transgene copy number and wound-induced GUS expression was observed in the leaves of win3.12T plants. More importantly, the win3.12T promoter affected a strong systemic activity in aerial parts of potato in response to fungal infection (Fusarium solani), that was several-fold higher than even in local response to mechanical wounding. This is a first report of a tree promoter systemically activated in response to fungal infection in a heterologous host (potato). The win3.12T promoter clearly harbours regulatory elements highly responsive to pathogen invasion, and responds to common signal molecules that mediate remote wound/infection responses in both angiosperm species.